The present invention relates to a power consumption reduction method in a digital mobile radio system as defined in the preamble of claim 1.
The present invention further relates to a mobile radio station.
Such a power consumption reduction method is described in Chapter 8.1.3 of the Draft European Telecommunication Standard ETS 300 578, Ninth Edition, March 1997 as published by ETSI, xe2x80x9cGSM Digital cellular telecommunications system (Phase 2); Radio subsystem link control (GSM 05.08)xe2x80x9d. Generally, in digital mobile radio systems, such as a GSM system, RF power control is employed to minimize the transmit power required by a mobile or a base station subsystem whilst maintaining the quality of the radio links. By minimizing the transmit power levels, interference to co-channel users is reduced. Moreover, in a mobile it is important to save power because increased battery life increases call times and standby times. For the latter reason, manufacturers of mobiles are continuously striving to reduce power consumption in mobiles. In Chapter 8.1.3 of said ETSI document, it is prescribed how a mobile, in a dedicated mode, i.e. when assigned to a traffic channel or to a dedicated control channel, should perform received signal strength measurements on BCCH carriers of neighbouring cells. Such BCCH carriers are broadcast control channels for broadcasting general information on a transceiver base station per base transceiver station basis. In GSM, radio frequency channels are defined, and numbers are allocated to all the radio frequency channels available to the system. Each cell is allocated a subset of these channels, defined as the cell allocation. The BCCH carrier is a special radio frequency channel of the cell allocation which is used to carry synchronization information and said general information, including the organization of the so-called common control channels such as paging channels, random access channels, and access grant channels used for setting up radio links between mobiles and the GSM network. In Chapter 8.1.3, it is described that a mobile shall perform at least one power measurement on a neighbour cell carrier in evert TDMA (Time Division Multiple Access) frame. The measurements are reported to the radio network via a control channel. The radio network can make a handover decision on the basis of these measurements and/or on the basis of further measurements in the mobile and/or the radio network. The described method is not optimal as regards power saving in the mobile.
It is an object of the present invention to provide a power consumption reduction method in a mobile radio system whilst a mobile radio station is in a dedicated mode, in which power measurements on neighbour cells are optimized.
To this end the power consumption reduction method as defined in the preamble of claim has the characterizing features as claimed in the characterizing part of claim 1. Herewith, the mobile can be powered down during greater periods of time so that more power savings are obtained.
The present invention is based upon the insight that optimum use of the mobile""s hardware, i.e. quick synthesizer stabilization and performing an optimum number of measurements per frame, creates the possibility to squeeze more measurements in a single frame, and that, therefore, other frames can contain less power measurements or even no power measurements at all. In these xe2x80x98silentxe2x80x99 periods, the mobile can adopt a power down mode. Herewith, more power savings are obtained as when applying the GSM Standard, and thus a longer call and standby time of the mobile. It is realized that the claimed method goes against the GSM Standard, but a proposal could be made for modifying the Standard. Furthermore, the far more optimal method as claimed in claim 1 could advantageously be applied in future mobile radio standards.
Embodiments are claimed in the dependent claims.